SENSORY ORIGINS OF MASKED PRIMING: PRIME-TRAGET CONGRUENCY AND CONGRUENCY BASE RATE ALTER VISUAL TARGET DISCRIMINABILITY
Perceptual priming studies commonly use response latencies and error rates to infer if primes affect motor responses or sensory representations as well. Here, we use signal detection theory (SDT) analysis to address this issue, varying both prime-target congruency and non- sensory context of the task (serial presentation order and base rates of congruent and incongruent trials). Participants pressed a respective key, promptly deciding whether or not the target square had gaps in its outline. In a trial, two other stimuli were presented prior to the target: either a congruent or an incongruent prime (same/different square, respectively) and a mask (square with dashed outline). In between-subject designs, we varied the frequency of congruent and incongruent trials in the series (1:1, 1:3, and 3:1) and serial order of their presentation (either frequent or infrequent - congruent or incongruent - trials were more, or equally, likely to occur at the series outset). The results indicate (1) a reliable priming of target discriminability (i.e., enhanced congruent trials), (2) a congruency Ã— base rate interaction for discriminability, such that frequent incongruent trials abolish discriminability priming, but (3) no priming for decision/response criteria. We conclude that with masked priming of visual identification, both sensory (prime-target congruency) and non-sensory variables (base rates of congruent and incongruent trials) modulate target discriminability, affecting sensory representations, rather than decision criteria and/or response tendencies.